The NEW EGO 21 Self-Propelled mower with (2) 5.0Ah Batteries provides longer run time. Its PeakPower technology combines the power of 2 EGO batteries for longer run time and efficient power draw. The push start button provides a quick and easy start, while the self-propel speed control allows you to power through tough terrain at your personal preference. The advanced EGO POWER+ 56-Volt battery uses industry-leading Arc-Lithium technology to deliver superior power and is compatible with all EGO POWER+ products.